Turbomachinery with integrated pump

ABSTRACT

The disclosed embodiments include self-lubricating oil feed systems that may include an integral bearing. The oil feed systems may include gear pumps suitable to minimize the axial profile of the oil feed systems. Additionally, the oil feed systems may be directly coupled to turbomachinery having a gear, and provide for mechanical support and lubrication of certain components of the turbomachinery. In certain embodiments, the oil feed systems enables the transfer of a lubrication fluid to the bearing during operations of the turbomachinery.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Pumps enable the flow of a fluid through various mechanical systems,such as turbomachinery. Turbomachinery may include pumps, turbines, andcompressors. The pump may enable lubrication, cooling and/or sealing ofthe turbomachinery, thus increasing the operational life and efficiencyof the turbomachinery. For example, heat generated by the turbomachinerymay be transferred to a fluid and then transferred to a cooling medium.Likewise, the fluid may lubricate various mechanical components of theturbomachinery, decreasing friction between the components.Unfortunately, the pump may take valuable space, increasing thefootprint of the turbomachinery.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a schematic view of a turbomachinery including a bearing oilfeed system, in accordance with one embodiment of the disclosure;

FIG. 2 is a perspective top view of a compressor including the bearingoil feed system of FIG. 1, in accordance with one embodiment of thedisclosure;

FIG. 3 is an exploded perspective side-view of components of a bearingoil feed system and a gear, in accordance with one embodiment of thedisclosure;

FIG. 4 is a cross-sectional side-view of the bearing oil feed system andgear of FIG. 3; and

FIG. 5 is a cross-sectional top view of a crescent gear pump.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top,” “bottom,” “above,” “below,” and variationsof these terms is made for convenience, but does not require anyparticular orientation of the components.

The disclosed embodiments include a bearing oil feed system including agear pump, such as a crescent gear pump. The bearing oil feed system mayalso include a bearing support system, such as a sleeve bearing. Incertain embodiments, the bearing oil feed system may be incorporated inturbomachinery, such as a compressor, a pump, or a turbine, and used tomechanically support as well as lubricate certain components of theturbomachinery. In one embodiment, the gear pump is a crescent gear pumpthat minimizes its axial length by incorporating two gears inside of apump housing. In other embodiments, the gear pump may be a spur gearpump (e.g., pump having two side-by-side meshing spur gears), a helicalgear pump (e.g., pump having meshing helical gears), or a gerotor pump(i.e., generated rotor pump), also suitable for minimizing the gearpump's axial length. Additionally, the bearing oil feed system,including the gear pump, may be recessed within the turbomachinery,further reducing an axial profile of the bearing oil feed system.

The integrated bearing system of the bearing oil feed system may supporta gear included in a rotor of a turbomachinery, such as a compressor.For example, the gear may include a “bull” gear of the compressorsuitable for driving one or more compressor scrolls. Additionally, thebearing oil feed system may supply a lubricant and/or coolant, such asoil, to various regions of the integrated bearing (e.g., sleeve bearing)as well as to other components of the turbomachinery. Indeed, thebearing oil feed system may use integral passages in the bearing and/orin the turbomachinery to deliver the lubrication and/or cooling fluid.Such integral passages include internal bores formed by drilling,casting, milling, and so forth. The integral passages may also be usedto couple the gear pump and bearing system to an integral modularlubrication system. The integral modular lubrication system may furtherreduce the size and profile of the turbomachinery by integratingcomponents such as a filter, heat exchanger, thermal regulator, andvalves with the turbomachinery, further streamlining the turbomachinerysize and geometric profile. Indeed, an improved lubrication systemhaving enhanced suction life capabilities and reduced noise may beconstructed using the embodiments disclosed herein.

With the foregoing in mind and turning to FIG. 1, the figure is aschematic view of an embodiment of a turbomachinery 10 including a rotor12 and a bearing oil feed system 14. The bearing oil feed system 14 mayfurther include a gear pump 16 and a bearing system 18 integrated withina turbomachinery component, such as a rotor 12. The figure is alsoillustrative of an embodiment of an integral modular lubrication system20 that is suitable for lubricating components of the turbomachinery 10.Indeed, the integral modular lubrication system 20 may be integratedwith the turbomachinery 10 and include internal or integral passagessuitable for use as fluid conduits between components of theturbomachinery 10 and the integral modular lubrication system 20. Theuse of internal or integral passages may reduce or eliminate the use ofexternal piping for the conduit lubrication fluid. The turbomachinery 10may be any type of turbomachinery, such as a compressor, a pump or aturbine. The rotor 12 may be any type of rotating device that wouldbenefit from lubrication. For example, the rotor 12 may be a rotor 12that includes a “bull” gear of a centrifugal compressor, as described inmore detail below with respect to FIG. 2.

During rotor operations, the rotor 12 may rotate about an axis, directlyor indirectly driving a load such as a compressor scroll 22. It is to beunderstood that any mechanical load may be directly or indirectlycoupled to the rotor 12 in addition to or alternative to the compressorscroll 22. For example electrical generators, other scrolls, vanes,blades, and so forth, may be coupled to the rotor 12. The rotor 12 isalso coupled to the gear pump 16. Accordingly, the rotation of the rotor12 may also drive the gear pump 16, creating a suction force or liftsuitable for transferring a lubrication fluid from an oil tank 24 intothe bearing oil feed system 14. In certain embodiments, the fluid may betransferred through integral passages 26. That is, passages or bores 26internal to the turbomachinery 10 and/or rotor 12 may be used to directthe lubrication fluid into the bearing oil feed system 14. In this way,the use of external plumbing and/or feed lines is minimized oreliminated, resulting in the turbomachinery 10 having a more streamlinedgeometry or profile. The integral passages 26 may be formed by anysuitable technique, such as drilling, casting, milling, and so forth.

The lubrication fluid may be used to lubricate any number of componentsof the turbomachinery 10, including the rotor 12. Indeed, thelubrication fluid may be further distributed to lubricate seal faces,other bearings, gears, and so forth. The gear pump 16 may alsodistribute the lubrication fluid to the bearing system 18 and/or to theintegral modular lubrication system 20. Indeed, the bearing system 18included in the bearing oil feed system 14 is a self-lubricating bearingsystem 18, in which an increase in the rotational motion of the rotor 12results in additional lubrication of the bearing system 18 as describedin more detail below.

The gear pump 16 may also direct the lubrication fluid into the integralmodular lubrication system 20 for further processing, by using, forexample, internal or integral passages 28. In other examples, externalpassages such as pipes or conduits may be used by the gear pump 16 todirect the lubrication fluid into the integral modular lubricationsystem 20. The integral modular lubrication system 20 may then filterthe lubrication fluid by using a filter or strainer 30 suitable forremoving particulate matter or otherwise for cleaning the lubricationfluid. The lubrication fluid may then be directed via internal passages32, for example, into a heat exchanger 34 (e.g., cooler) suitable forcooling the lubrication fluid. More specifically, the heat exchanger 34may cool the lubrication fluid by directing the lubrication fluidthrough a cooling medium, such as a gas or a liquid. Heat from thelubrication fluid may then transfer to the cooling medium, therebyreducing the temperature of the lubrication fluid.

In certain embodiments, a thermal regulator 36 may be included in theintegral modular lubrication system 20. The thermal regulator 36 enablesa more constant operating temperature for the lubrication fluid, forexample, by using an integral passage 38 to bypass the heat exchanger 34so as to maintain a more uniform operating temperature. For example, ifthe lubrication fluid is below a certain temperature, then no coolingmay be needed. Accordingly, the integral passage 38 may be used tobypass the heat exchanger 34. Additionally, a pressure relief valve 40may be used to maintain lubrication fluid pressure within a certainrange. For example, should a pressure of the lubrication fluid exceed acertain limit, the pressure relief valve 40 may redirect a portion orall of the lubrication fluid flow into the oil tank 24 by using anintegral passage 42, thus relieving the pressure. Otherwise, thelubrication fluid may be directed to flow into the turbomachinery 10 andthe rotor 12 through integral passages 44. An integral passage 46 maythen be used to transfer the lubrication fluid into the oil tank 24 forfurther reuse. By employing a bearing oil feed system 14 and an integralmodular lubrication system 20, the turbomachinery 10 may includeenhanced lubrication capabilities while also minimizing size, axiallength, and reducing or eliminating the use of external pipes orconduits.

FIG. 2 is a perspective top view of an embodiment of a turbomachinery 10(e.g., centrifugal compressor 50), including the bearing oil feed system14 directly coupled to the rotor 12. In the depicted embodiment, threescrolls, 22, 52, and 54 are connected to the rotor 12 through a “bull”gear 56. The scrolls 22, 52, and 54 are suitable to compress orpressurize a fluid, and may be used in stages. For example, the scrolls22, 52, and 54 may be used to force a refrigerant fluid outwardly,exerting a centrifugal force on the fluid. In one example, scroll 22 maybe used as a first stage scroll, scroll 52 may be used as a second stagescroll, and scroll 54 may be used as a third stage scroll. The fluid maybe compressed at a higher ratio at each successive stage, resulting inan efficient, high-ratio compression of the fluid. Larger diameterscrolls allow for a higher intake of fluid and a corresponding increasein compressor production. By axially reducing the length of the bearingoil feed system 14, the diameters of the scrolls 22 and 52 may beenlarged. Indeed, an axially short bearing oil feed system 14 may enablethe reduction or elimination of a distance d separating the two scrolls22 and 52. In one embodiment, the reduction of the axial protrusion ofthe bearing oil feed system 14 enables the two scrolls 22 and 52 to beapproximately adjacent to each other, with no separation distance d.Accordingly, the bearing oil feed system 14 may include pumps havingminimal axial lengths, such as gear pumps, and may be recessed into the“bull” gear 56 so as to enable the reduction or elimination of theseparation distance d. Additionally, the bearing oil feed system 14 maybe directly coupled to the gear 56 of the rotor 12, thus providing for aself-lubricating bearing oil feed system 14 that may also pump lubricantfluid to other components of the compressor 50.

FIG. 3 is an exploded side view of embodiments of the “bull” gear 56 andthe bearing oil feed system 14 of FIG. 2. In the depicted embodiment, ashaft 58 included in the bearing oil feed system 14 and may be used todirectly couple the bearing oil feed system 14 to the gear 56. Morespecifically, the shaft 58 may axially traverse the bearing system 18,and couple with a set of gears 60 and 62 of the gear pump 16. The gears60 and 62 may be disposed inside of a gear housing 64, which may besecurely connected to the bearing system 18 by using fasteners such asthreaded bolts. The shaft 58 of the bearing oil feed system 14 may thenbe coupled to a shaft 66 of the “bull” gear 56. The direct coupling ofthe shaft 66 to the “bull” gear 56 enables the gear pump 16 to pumpwhenever the “bull” gear rotates, as described below.

As the compressor 50 rotates the gear 56 around an axis, such as theY-axis, the shaft 58 coupled to the gear 56 also rotates about the sameaxis. The bearing system 18 and housing 64 remain approximatelystationary, enabling the gear 56 to rotate axially with respect to thebearing system 18 and the housing 64. However, since the shaft 58 iscoupled to the gears 60 and 62, the gears 60 and 62 rotate with respectto the housing 64. The rotating gears 60 and 62 create a suction liftsuitable for transferring lubrication fluid from the oil tank 24 (shownin FIG. 1) into the housing 64 through an inlet port 68. In someembodiments, the lubrication fluid may be further directed into certainregions of the bearing system 18, such as an outer cylinder wall 70 ofthe bearing system 18, as described below with respect to FIGS. 4 and 5.In these embodiments, further rotation of the gear 56 will causeadditional transfer of the lubrication fluid into the bearing wall 70.Indeed, the self-lubrication bearing system 18 may transfer lubricationfluid based on the rotational motion of the gear 56.

FIG. 4 is a cross-sectional view of the bearing oil feed system 14recessed into the gear 56 and directly coupled to the gear 56 by usingthe shaft 58. As mentioned above, the bearing system 18 of the bearingoil feed system 14 may be used as a main bearing (e.g., sleeve bearing)suitable for enabling a mechanical support of the gear 56. Accordingly,an outer diameter of the cylinder wall 70 of the bearing system 18 maybe approximately equal to an inner diameter of an inner chamber 72 ofthe gear 56. The bearing system 18 may then be recessed into the chamber72, with the shaft 58 used to securely couple the bearing system 18 (andattached gear pump 16) to the shaft 66. The two shafts 58 and 56 maythen mechanically support the gear 56 and enable the rotation of thegear 56 about an axis 67, such as the depicted Y-axis.

In the illustrated embodiment, rotation 67 of the gear 56 about theY-axis results in an equivalent rotation 67 of the shaft 58.Accordingly, the gears 60 and 62 connected to the shaft 58 will alsorotate. The rotation of the gears 60 and 62 may create a suction effector lift. More specifically, the rotation of the gears 60 and 62 maycreate an expanding volume on an inlet port 68, which in turn creates avacuum suitable for suctioning a flow 73 of lubrication fluid into thegear pump 16. The lubricant fluid may then be contained or trappedinside internal voids such as a void defined by teeth of the gears 60and 62 as described in more detail below with respect to FIG. 5. Furtherrotational motion of the gears 60 and 62 may result in the lubricationfluid being displaced into an outlet port 74, resulting in an outwardlyflow 75. In certain embodiments, the outlet port 74 may be connected tothe integral modular lubrication system 20 (shown in FIG. 1), as well asto other components of the turbomachinery 10. Accordingly, the fluidflow 75 may be used by the integral modular lubrication system 20 and/orother turbomachinery 10 components for lubrication and cooling.

As illustrated, an integral passage 76 may be used to direct lubricationfluid to the integral modular lubrication system 20 and/or othercomponents of the turbomachinery 10. Indeed, the integral passage 76 maydirect lubrication fluid through the inside of the gear pump 16 andbearing system 18 for further use by the turbomachinery 10, eliminatingthe need for external conduits. Additionally, an integral passage 78 maytransfer lubrication fluid from the integral passage 76 into thecylindrical wall 70 of the bearing system 18. By enabling a flow oflubrication fluid into the integral passage 78, an interface between thecylindrical wall 70 of the bearing system 18 and the inner chamber 72 ofthe gear 56 may be kept suitably lubricated. It is to be understood thata variety of gear pumps 16 may be used for transferring lubricant in thebearing oil feed system 14, such as a spur gear pump, a helical gearpump, a gerotor pump, or a crescent gear pump, which is described inmore detail with respect to FIG. 5. For example, in a spur gear pump,two spur or star gears may be positioned side-by-side, with the twogears intermeshing with one another. In a helical gear pump, the twointermeshing gears may include a helical twist enabling a smoother flowof fluid. In a gerotor pump, a trochoidal inner rotor may be placedinternal to an outer rotor having circular arcs.

FIG. 5 is a cross-sectional top view of an embodiment of the gear pump16 including a crescent 80, and the gears 60 and 62. As depicted, thepump 16 includes multiple openings 82 suitable for attaching the pump 16to the bearing system 18 (shown in FIG. 4), e.g., with fasteners such asbolts. Also depicted in this embodiment is the flow 73 of lubricationfluid entering the gear pump 16 through the inlet port 68. Such a flow73 may be caused by the rotation of the gears 60 and 62 which in turnmay be caused by a rotation of the shaft 58. The shaft 58 may couple togear 62 by extending into bore 69 of the gear 62, and then a key insertof the shaft 58 may interlock with key slots 71 to secure the shaft 58.The rotation of the gears 60 and 62 may cause the lubrication fluid flow73 to enter the pump 16 and into voids between teeth of the gears 60 and62. As the flow 73 enters the pump 16, the crescent 80 divides theliquid flow 73 and may also act as a seal between the inlet port 68(i.e., suction port) and the outlet port 74 (i.e., discharge port).Eventually all of the voids in the pump 16 become flooded with liquid.Continued rotation of gears 60 and 62 then results in an intermeshing ofthe gears' teeth, forcing the liquid between the voids to exit throughthe outlet port 74 (e.g., as the flow 75). Indeed, the gear pump 16enables a non-pulsatile or continuous movement of fluid while using onlytwo moving parts (i.e., gears 60 and 62). Additionally, the gear pump 16exhibits improved noise reduction because of the reduced number ofmoving parts, while increasing the suction force or lift when comparedto other pumps, such as screw pumps.

In one embodiment, the integral passage 76 may be disposed in a metalcylinder 84 of the pump 16 and used to direct some of the lubricationflow 73 into the integral passage 76. As mentioned above with respect toFIG. 4, the integral passage 76 may direct the lubrication fluid intothe wall 70 of the bearing system 18 and/or into the integral modularlubrication system 20. In this embodiment, additional rotation of thegears 60 and 62 self-lubricates the bearing system 18. That is, therotation of the gears 60 and 62 directs additional lubrication fluidinto the wall 70 of the bearing system 18 through the integral passage76 and then to the integral passage 78 (shown in FIG. 4). Indeed,continuous operation of the gear pump 18 results in a continuouslubrication of the bearing system 18 without the need to add othersystems such as computer-based controllers. Further, the bearing oilfeed system 14 may support a turbomachinery component, such as the gear56. Additionally the bearing oil feed system 14 may provide for suitablelubrication of other turbomachinery components. The use of gear pumpsand the embedding of the bearing oil feed system 14 into the gear 56substantially reduces the axial protrusion of the bearing oil feedsystem 14. This reduced axial profile enables certain turbomachinery 10,such as the compressor 50, to include larger scroll sizes with acorresponding improvement in compression efficiencies.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A system comprising: a rotor coupled to abearing; a gear pump directly coupled to the bearing via one or morethreaded fasteners, wherein the gear pump is configured to route alubricant to the bearing; and a first shaft drivingly coupled to therotor and the gear pump, wherein the first shaft, the rotor, and thebearing axially overlap with one another.
 2. The system of claim 1,wherein the rotor comprises a second shaft directly coupled to the firstshaft of the gear pump.
 3. The system of claim 1, wherein the rotorcomprises a gear, wherein the gear pump is recessed axially within abore of the gear, the bearing is disposed within the bore of the gear,and the first shaft extends axially through the bearing.
 4. The systemof claim 1, wherein a housing of the gear pump is directly coupled to awall of the bearing via the one or more fasteners, the wall covers anopening into a cavity of the housing, and one or more gears of the gearpump are disposed inside of the cavity.
 5. The system of claim 4,wherein the housing and the wall are stationary relative to the rotor.6. The system of claim 1, wherein the gear pump comprises a crescentgear pump, a spur gear pump, a helical gear pump, or a gerotor pump. 7.The system of claim 1, wherein the rotor comprises integral passagesdirectly coupled to the gear pump.
 8. The system of claim 1, comprisinga compressor, wherein the rotor is disposed in the compressor.
 9. Thesystem of claim 8, wherein the compressor comprises an integral modularlubrication system, and the integral lubrication system is configured tocontrol one or more parameters of the lubricant.
 10. The system of claim8, wherein the integral modular lubrication system, comprises a filter,a heat exchanger, a thermal regulator, a valve, or a combinationthereof.
 11. A system comprising: a bearing lubricant feed systemconfigured to couple directly to a rotor, wherein the bearing lubricantfeed system comprises: a housing having an opening into a cavity; a gearpump integrated with the housing inside the cavity; a bearing having awall coupled to the housing over the opening via one or more threadedfasteners, wherein the bearing is configured to enable a rotation of therotor; a shaft extending axially through the bearing, wherein the shaftis coupled to the gear pump, the shaft is configured to couple to therotor, and the bearing is configured to mount within a bore of the rotorbetween the shaft and the rotor; and a lubricant feed passage integratedwith the housing, wherein the lubricant feed passage extends to thebearing, and the lubricant feed passage is configured to deliver alubricant to the bearing.
 12. The system of claim 11, comprising anintegral modular lubrication system, wherein the integral modularlubrication system is fluidly coupled to the bearing lubricant feedsystem through a conduit configured to deliver the lubricant.
 13. Thesystem of claim 12, wherein the conduit comprises an internal passagewaybetween the bearing lubricant feed system and the integral modularlubrication system.
 14. The system of claim 12, wherein the conduitcomprises an external passageway between the bearing lubricant feedsystem and the integral modular lubrication system.
 15. The system ofclaim 12, comprising a compressor integrated with the integral modularlubrication system, wherein the integral modular lubrication system isconfigured to deliver the lubricant to the compressor.
 16. The system ofclaim 12, wherein the integral modular lubrication system comprises afilter, a heat exchanger, a thermal regulator, and a valve.
 17. Thesystem of claim 11, wherein the gear pump comprises a crescent gearpump, a spur gear pump, a helical gear pump, or a gerotor pump.
 18. Asystem comprising: a bearing lubricant feed system configured to mountinto a recess of a rotor, wherein the bearing lubricant feed systemcomprises: a housing having an opening into a cavity; a gear pumpintegrated with the housing inside the cavity; a bearing having a wallcoupled to the housing over the opening via one or more threadedfasteners, wherein the bearing is configured to enable a rotation of therotor; a shaft extending axially through the bearing, wherein the shaftis coupled to the gear pump, and the shaft is configured to couple tothe rotor; and a lubricant feed passage having an inlet port and anoutlet port, wherein the gear pump is configured to transfer a lubricantfrom the inlet port into the outlet port, wherein the bearing isconfigured to mount into the recess of the rotor, wherein the housingand the wall of the bearing remain stationary, wherein the bearinglubricant feed system is configured to supply the lubricant to thebearing in the recess of the rotor.
 19. The system of claim 18,comprising an integral modular lubrication system configured to processthe lubricant, wherein the integral modular lubrication system isfluidly coupled to the outlet port or the inlet port.
 20. The system ofclaim 18, wherein the gear pump comprises a crescent gear pump having acrescent and a first and a second gear, and the first and second gearsrotate while the crescent remains stationary.
 21. The system of claim 1,wherein the gear pump is directly coupled to the bearing along axiallyabutting surfaces, and the bearing closes an opening into a chamber ofthe gear pump.
 22. The system of claim 1, wherein a housing of the gearpump comprises a chamber having a first gear and a second gear, whereinthe housing is configured to route the lubricant from the chamber,through an internal passage separate from the first and second gears,and to the bearing.
 23. The system of claim 1, wherein the bearing isrecessed into a central bore along an axis of the rotor, and the gearpump is recessed into the bearing.
 24. A system, comprising: a gearpump, comprising: a housing having a chamber; a first pump gear disposedin the chamber; a shaft drivingly coupled to the first pump gear; abearing coupled to the housing; a lubricant passage configured to routea lubricant to the bearing; and a rotor mounting interface, wherein therotor mounting interface comprises a shaft interface configured todrivingly couple the shaft to a rotor and a bearing interface configuredto interface the bearing with the rotor, wherein the shaft, the bearing,and the bearing interface axially overlap with one another.
 25. Thesystem of claim 24, wherein the rotor comprises a gear, the bearing isrecessed into a bore in the gear, and the shaft extends axially throughthe gear and the bore.
 26. The system of claim 24, comprising acompressor having the rotor and the gear pump.
 27. The system of claim24, wherein the bearing is a wall portion of the housing.
 28. The systemof claim 24, wherein the bearing comprises a sleeve bearing portionextending axially from an end cover portion, and the end cover portionextends across an opening into the chamber.
 29. The system of claim 24,wherein the gear pump comprises a crescent gear pump having a crescent,the first pump gear, and a second pump gear, wherein the first andsecond pump gears are configured to rotate while the crescent remainsstationary.
 30. The system of claim 24, wherein the housing, the firstpump gear, the shaft, the bearing, the lubricant passage, and the rotormounting interface are assembled together into a single unit forming thegear pump.